Grid former



Dec. 20, 1955 c. B. MARSHALL ETAL 2,727,540

GRID FORMER Filed June 1, 1954 2 Sheets-Sheet 1 INVENTORS: HARVEY H.HETR|CK $HESTR B. MARSHALL YLVQ.

Dec. 20, 1955 c. B. MARSHALL ETAL 2,727,540

GRID FORMER Filed June 1, 1954 2 Sheets-Sheet 2 INVENTOR HARVE .HETRICS cues a. MARSH BY y,

United States 2,727,540 GRID FORMER Chester B. Marshall, Mill Hall, and Harvey H. Hetriclr, Brookville, Pa., assignors to Sylvania Electric Products Inc., a corporation of Massachusetts Application June 1, 1954, Serial No. 433,522 5. Claims. (Cl. 140-715) This invention relates to a, grid forming adjunct for use with a machine for automatically making grids which may be of the type utilized in electron discharge tubes.

in a grid making machine such as is disclosed in the application to Gartner and Smith, Serial No. 771,995, filed September 3., 1947, there is a mandrel about which a string of grids is wound, the wound string being drawn off the mandrel and cut to grid lengths. Sometimes, as I is disclosed in the above mentioned application, the grid is additionally stretched to straighten the grid side rods. The grid thus obtained may be of any cross-section,

such as elliptical or circular; the exact cross-sectional.

area being determined by the cross section of the mandrel about which the grid laterals are wound. Sometimes it is found desirable to reshape the grid inorder to form areas which in cross section are symmetrical with and surround the cathode with in order to obtain better control of the cathode emission. For example, it may be desired to form the .grid with reentrant portions where the grid laterals approach the grid side rods. in the past, the final grid forming was accomplished on another machine.

which thc grid is to he used It is an object of this invention to provide vforming means on the grid making machine itself .and thereby avoid the use of an extra machine with attendant extra handling.

it is a further object of the invention to] simplifyh combined grid making and final forming machine by replacing the gripping jaws on one of the drawing heads, normally employed to advance the grid string as the grid is being made in a grid making machine, by a combined grid string advancing and grid forminghead.

it is a still further object of this invention to associate with such a forming means, a mandrel which is extensible with head advancement and retractable on release of the head to contribute toward continuous grid making and forming.

These and otherobjects will be apparent after reading the following specification and claims in conjunction with the accompanying drawings in which Fig. 1 fragmentarily represents the grid string making and advancing end of a grid machine with an adjunctive or supplemental mandrel to facilitate ,grid forming.

Fig. 2 is an enlarged view of the supplemental mandrel and adjacent portions, the mandrel beingshown in a fully retracted position. y

3 is a cross-sectional view of a :grid and mandrel on the line 3-3 of Fig. 2.

Fig. 4 is a cross-sectional view of the grid in thesupplemental grid former, with the forming and grid advancing head shown with its jaws in separated relation.

Fig. 5 is a cross-section on the broken line 55 of Pig. 4 with the jaws shown in gripping relation about the formed grid and Fig. 6 is a section in the line 6-6 of Fig. 2.

Referring to the disclosure in greater detail, at 10 there is indicated the stationary mandrel of a grid winding machine about which mandrel is rotatable the spool .12, see Fig. 1, to lay a wire and wind 2. grid along the travelling side rods 14 and 16, as is .old in the art. These side rods are fed from spools, not shown, through guides 17 to the laying device. A string of grids with sections isolated from each other is formed on the side rods with the aid ofthe mandrel 10 and other mechanism not de scribed since this mechanism forms no part of the invenof guiding the movement of the side rods and yet permitting movement of the Wound grid string around the mandrel without too much drag, the mandrel is formed with a pair of recesses 18, 20, along which the rods move.

In prior art machines, the mandrel terminates at a position 22 slightly beyond the station at which the grid wire is wound about the side rods and in such machines there is provided a number of heads of which only 24 and 26, are shown, operating in proper timed relationship to one another to continuously draw the wound grid string off from the mandrel, to stretch the grid side rods, and to cut the grid strip into grids of appropriate lengths. For this purpose the feeding and stretching heads reciprocate in a direction along the axis of the mandrel. The means for moving the feeding heads are not disclosed since that also is not part of the present invention. However, should any further details of the structure above described be desired, reference may be made to the application 771,995 previously referred to.

With this invention the first feeding and stretching head 24 is modified in order to shape the wound grids to .conform with the exterior of a cathode with which the grid is to be associated.

The remaining feeding heads of which only head 26 is shown are provided with side rod indenting and gripping means, as is old in the art, to assist in feeding the grid string. With the modified head 24- there is also associated :a supplemental mandrel structure 23 as will be described.

To the end face 22 of the mandrel lti there is welded or otherwise suitably fixed a tube 36, here, for purposes of illustration, shown aselliptical, extending to a position close to the drawing head 24 when the head is at the left :hand end of its stroke. Loosely fitted within the tube is the 'flat bar stem 32 of a retractable supple- .mentalforming mandrel 34. The stem 32 is drawn into the tube by av coiled spring 36 tensioned between a .pin 38 driven through the tube and a fastening means 40 on the end of the stern. This fastening means may be a soldered or welded joint or an eyelet at the end of the stem receiving a hooked portion of the spring. The free or exposed end of the stem is made of the cross-section to .assist in shaping the desired form of grid and of .a length a little longer than the length of a grid section along the side rods. Thus, if the grid is to surround a cylindrical cathode, the exposed end of the supplemental If a rectangular cathode .is to be associated with the grid, the end of the mandrel .34 wouldbe rectangular in cross-section. The shaped end of the mandrel, in retracted position of the mandrel, extends beyond the tube 28 .and in position to lie within the confines of head 24, when the head is close .to the winder.

Cooperating with the mandrel 34 are the forming dies 42 and 44. The .upper formingadie A2 is easily removably attached as by means of machine screw 45, to a slide 48 operating in suitable ways mounted on the head 24 and reciprocating vertically in proper timed sequence with the grid wire winding about the side rods. The lower forming die 44 is similarly attached, as by means of machine screw 50, to a lower vertically reciprocable slide 52 guided for movement on the head 24. Both slides 48 and 52 are operated in synchronism with each other to simultaneously approach the wound grid string on the mandrel 34 to shape the same about the mandrel and g finished section 54 in the grid string.-

thereby form a The opposing faces or jaws of the dies are configurated to conform with the shape of the cathode with which the grid is to be associated, the configuration here shown resulting in the formation of a grid, the longitudinal central portion of which is cylindrical and the portions adjacent to the side rods 14 and 16 being reentrant,

resulting in a grid with undulating surfaces extending from one side rod to the other. The second head 26, also has slides provided with gripping faces, not shown, designed to engage only the side rod portions between grid sections to advance the grid string.

In operation, both heads 24 and 26 while advancing the grid string, move together at the same rate. However, the jaws engage the grid string at different times but always in overlapping relation so that at no time is the grid string released from both of the jaws.

When the jaws or dies 42, 44 of the first head engage I a grid of the grid string, it configurates the grid according to the surface of the grid rods, the free end of mandrel 34, and the die configuration, while drawing the grid string to the right as viewed in Fig. 2. At this time, since the jaws tightly shape the grid about the mandrel 34, the

mandrel is drawn along with the head, elongating and further tensioning the spring 36. Upon release of the dies 42 and 44 preparatory to return of the head 24 for a new bite on a grid of the grid string, the now released mandrel 34 is withdrawn by the spring 36 to its original position, ready for cooperation with the next grid of the string.

Having thus described the invention what is claimed as new is:

1. In a grid winding and forming machine in which there are means for winding a grid string and a point of discharge for said string, a grid clamper and former head movable to a first position to the said point of discharge and movable to a second position away from the point of discharge to withdraw the grid string, a forming mandrel of a shape to conform with a portion of the former head within the grid string at said first position, said head when at said first position shaping grid wires of said grid string about said mandrel and clamping the mandrel and grid wires to the head, said mandrel moving with the shaped wires and head on the movement of the head to the second position, said head opening at the second position to release the grid string and mandrel, and means operative on said head opening to withdraw the mandrel from the shaped portion of the grid string to its initial position within the unshaped portion.

2. In a grid winding and forming machine in which there are means for winding a grid string and a point of discharge for said string, a grid clamper and former head comprising a pair of cooperating dies movable toward and away from each other and movable to a first position to the said point of discharge and movable to a second position away from the point of discharge to withdraw the grid string, a forming mandrel of a shape to conform with a portion of the former head within the grid string at said first position, said dies when at said first position shaping grid wires of said grid string about said mandrel and clamping the mandrel and grid wires to the dies, said mandrel moving with the shaped wires and dies on the movement of the dies to the second position, said dies opening at the second position to release the grid string and mandrel, and means operative on said die opening to withdraw the mandrel from the shaped portion of the i string its initial 3. In a grid winding and forming machine in which A there are means for winding a grid string and a point of discharge for said string, a grid clamper and former head movable to a first position to the said point of discharge and movable to a second position away from the point of discharge to withdraw the grid string, a forming mandrel of a shape to conform with a portion of the former head within the grid string at said first position, said head when at said first position shaping grid wires of said grid string about said mandrel and clamping the mandrel and grid wires to the head, said mandrel moving with the shaped wires and head on the movement of the head to the second position, said head opening at the second position to release the grid string and mandrel, and resilient means tensioned between the mandrel and a fixed part of the machine within the grid winding operative to withdraw the mandrel from the shaped portion of the grid string to its initial position within the unshaped portion.

4. In a grid winding and forming machine having means for winding a grid string having side rods and grid laterals wound around the side rods and in which said winding means includes a main mandrel guiding the grid side rods as they travel therealong, a grid clamper and former head movable to a first position toward the main mandrel to grasp the grid string and movable to a second position away from the main mandrel to withdraw the grid string as it is being wound, said head releasing the grid string at said second position, a sleeve attached to the end of said main mandrel, a forming mandrel having a stem slidable in said sleeve, said forming mandrel at the outer exposed end thereof having a die portion lying within the grid laterals in a position to be clamped by the head at said first position thereof, said die portion being of a shape to correspond with the shape of an indirectly heated cathode, and means urging the sleeve and stem into telescoped relationship.

5. In a grid. winding and forming machine in which there is a means for winding a grid string having side rods and grid laterals wound around the side rods, and in which said winding means includes a main mandrel guiding the grid side rods as they travel therealong, a grid clamper and former head with a pair of cooperating die blocks movable toward and from each other, said head being movable to a first position toward the main ,mandrel to grasp the grid string and movable to a second position away from the main mandrel to withdraw the grid string as it is being wound, said head releasing the grid string at said second position, a sleeve attached to the end of said main mandrel, a forming mandrel having a stem slidable in said sleeve, said forming mandrel at the outer exposed end thereof having a die portion lying within the grid laterals in a position to be clamped by the head at said first position thereof, said die portion being of a shape to mate with the contours of the faces of the die blocks which oppose one another, and means urging the sleeve and stem into telescoped relationship.

References Cited in the file of this patent UNITED. STATES PATENTS 2,181,288 Washburn Nov. 28, 1939 2,426,522 Porter Aug. 26, 1947 2,441,228 Schneider May 11, 1948 2,586,629 Englert Feb. 19, 1952 

